1. Field of the Invention
This invention relates to a flying head slider employed in a magnetic disk drive, a magneto-optical disk drive, etc.
2. Description of Related Art
An apparatus having the same construction as a slider-type magnetic head employed in a hard disk drive has been known as a bias magnetic field generating apparatus for impressing a bias magnetic field to a magneto-optical disk (e.g., INTERNATIONAL SYMPOSIUM ON OPTICAL MEMORY 1987 September T. NAKAO et al.).
FIG. 1 is an enlarged perspective view showing the construction of a conventional slider-type magnetic head and its peripheral in a magneto-optical disk drive. In FIG. 1, a magnetic head 2 is provided to face the upper surface of a magneto-optical disk 1 (referred to as a disk hereinafter), flying at several .mu.m height by the dynamic pressure caused by the rotation of the disk 1 in a direction shown by a white arrow. The magnetic head 2 is a rectangular flat plate and is constituted by a slider 21 thinned approximately several .mu.m on the leading edge side and a bulk head 24 as a bias magnetic field generating unit. The bulk head 24 comprises a U-shaped core 22 buried at the central end of the trailing edge side of the slider 21 and a coil 23 wound around the curved portion of the core 22. The slider 21 of the magnetic head 2 is fitted to a supporting arm 5 via a gimbal spring 4, so that the magnetic head 2 is able to pitch (rocking in a radial direction of the disk 1) and roll (rocking in a peripheral direction of the disk 1) around a pivot (not shown) formed in the gimbal spring 4. Accordingly, the magnetic head 2 can follow up the deflection at the surface of the disk 1 by the rocking of the magnetic head 2. Moreover, the magnetic head 2 is movable in the radial direction of the disk 1 by advance and retreat of the supporting arm 5.
An optical head 3 is provided beneath the lower surface of the disk 1, confronting where a bias magnetic field is generated by the bulk head 24. The optical head 3 heats the bias magnetic field generating area when recording or erasing data thereby to form a reversed magnetic domain.
FIG. 2 is an enlarged view showing the construction of the conventional slider 21, more specifically, FIG. 2(a) is a side sectional view and FIG. 2(b) is a bottom view of the conventional slider. The slider 21 is a flat plate of 10 mm long, 8 mm wide and about 1 mm thick, beneath which enters the air caused by the rotation of the disk 1 from a longitudinal direction shown by a white arrow. A tapered part 25 is formed on the bottom face of the slider 21 at an angle .theta. (14.5 mrad) almost across the width of the slider 21 from a position about 0.4-0.8 mm away from the end face at the leading edge of the slider 21 towards the trailing end to the leading edge end face. Two grooves 26, 26 are extending in a longitudinal direction of the slider 21. The bulk head 24 mentioned earlier is built in the center of an end face at the trailing edge of the slider 21.
When the air enters below the tapered part 25 of the slider 21 in the above-described structure, the air flow is throttled, thereby generating the dynamic pressure and eventually buoyancy in a direction to lift the slider 21 of the disk 1.
Meanwhile, the disk 1 is always moving up and down as a result of the surface deflection thereof, and accordingly, the slider 21 is rolling and pitching. At this time, if an end of the slider 21 touches with the disk 1, a foreign substance 10 such as dust or the like adhering onto the disk 1 may be transferred as indicated by hatching in FIG. 2 to the tapered part 25. In such case as above, the flying characteristic of the slider 21 is worsened by the adhesion of the foreign substance 10, and its flying height decreases as described for example, in Treatise No. 86-1058B by Mikio Tokuyama et al. under the title of "Flying Characteristic of A Slider With Adhered Dust" in Japan Society of Mechanical Engineers, Vol. 53, No. 488. Particularly, different from a magnetic disk drive which can be sealed thereinside, since a magneto-optical disk drive is open to the air in order to exchange the disk 1, the foreign substance 10 more easily adheres to the disk 1 and further to the end of the slider 21 through contact of the disk 1 with the slider 21.
When the flying height reduces, the slider 21 is easier to be brought into contact with the disk 1. The worst of it is that the surface of the disk 1 may be scratched to decrease the reliability of the drive.
In the meantime, the tapered part 25 is formed approximately across the width of the conventional slider at the leading edge thereof, and the centers of the dynamic pressure of the slider are found in the vicinity of positions A1, A2 closer to the trailing edge than the tapered part 25. Therefore, when the slider 21 rolls following up the deflection of the surface of the disk 1, the stability of the rolling motion is influenced by the center positions of the dynamic pressure, that is, the stability becomes worse as the positions A1, A2 come closer to the center of the slider 21. If the stability of the rolling is deteriorated, the slider 21 collides with the disk 1, thereby finally breaking the disk 1. Since the dynamic pressure is smaller and the flying height of the slider is lower especially when loading/unloading, the poor stability of the rolling motion may cause frequent collisions of the slider 21 with the disk 1.
Moreover, if the stability during pitching decreases, the gap between the bulk head 24 and disk 1 (flying height) changes, and such problems that the bulk head 24 collides with the disk 1 thereby breaks the disk 1, that the impressing magnetic field onto the disk 1 changes whereby data onto the disk 1 cannot be recorded, etc., are brought about.